Synthesis, characterization and quantum chemical ab initio calculations of new dimeric aminocyclodiphosph(V)azane and its Co(II), Ni(II) and Cu(II) complexes

The complexes of type [M2LCl2] in which M = Co(II), Ni(II) and Cu(II) ions and L are 1,3-o-pyridyl-2,4-dioxo-2',4'-bis(3-benzoldithiazol-2-yl-2-iminothiophene) cyclodiphosph(V)azane, were prepared and their structures were characterized by different physical techniques (IR. UV-Vis, H-1 NMR, P-31 NMR, mass, TGA, DTA, XRD, SEM, magnetic moment and electrical conductance measurements). Ab initio calculations at the level of DFT B3LYP/6-31G(d) were utilized to find the optimum geometry of the ligand. Spectral characterization of the ligand was simulated using DT-DFT method. Infrared spectra of the complexes indicate deprotonation and coordination of the imine NH. It also confirms that nitrogen atoms of the pyridine group and thiazole group contribute to the complexation. NBO natural charges were computed and discussed in the light of coordination centers. Electronic spectra and magnetic susceptibility measurements as well as quantum chemical calculations reveal square planar geometry for Cu(II) and Ni(II) complexes and tetrahedral geometry for Co(II) complex. The elemental analyses and mass spectral data have justified the M2LCl2 composition of complexes. (C) 2012 Elsevier B.V. All rights reserved.